{
  "$schema": "https://openexercise.org/schema/v0/exercise.json",
  "aliases": [
    {
      "text": "Single Leg Extension",
      "kind": "common"
    },
    {
      "text": "Unilateral Leg Extension",
      "kind": "common"
    },
    {
      "text": "One-Leg Leg Extension",
      "kind": "common"
    },
    {
      "text": "Single-Leg Machine Leg Extension",
      "kind": "common"
    }
  ],
  "anatomy": {
    "muscles": [
      {
        "muscle": "rectus-femoris",
        "role": "prime-mover"
      },
      {
        "muscle": "vastus-lateralis",
        "role": "prime-mover"
      },
      {
        "muscle": "vastus-medialis",
        "role": "prime-mover"
      },
      {
        "muscle": "vastus-intermedius",
        "role": "synergist"
      }
    ],
    "joints": [
      {
        "joint": "knee",
        "actions": [
          "extension"
        ]
      },
      {
        "joint": "hip",
        "actions": [
          "isometric-stabilization"
        ]
      }
    ]
  },
  "classification": {
    "modalities": [
      "hypertrophy",
      "strength",
      "rehabilitation"
    ],
    "movement_patterns": [
      "isolation-knee-extension"
    ],
    "mechanics": "isolation",
    "force": "push",
    "kinetic_chain": "open",
    "laterality": "unilateral",
    "planes": [
      "sagittal"
    ],
    "contraction": [
      "dynamic"
    ],
    "level": "beginner"
  },
  "equipment": {
    "required": [
      [
        "selectorized-machine",
        "plate-loaded-machine"
      ]
    ]
  },
  "external_ids": {
    "wger": "71"
  },
  "id": "oec:single-leg-leg-extension",
  "instructions": {
    "setup": [
      "Adjust the backrest so that the machine's pivot axis aligns directly with the center of your knee joint.",
      "Set the lower roller pad so it rests comfortably against the front of your working lower shin, just above the ankle.",
      "Sit back firmly against the back pad, place one leg behind the roller, and grip the side handles to anchor your pelvis to the seat."
    ],
    "steps": [
      "Smoothly extend your knee by contracting your quadriceps until your working leg is nearly straight.",
      "Pause briefly at peak contraction without hyperextending the knee or allowing your hips to lift.",
      "Lower the weight under control back to the starting stretch position, maintaining constant tension.",
      "Complete the desired repetitions with one leg before repeating with the opposite leg."
    ],
    "breathing": "Exhale as you extend the leg and inhale as you lower the weight back down.",
    "cues": [
      "Pull yourself down into the seat.",
      "Drive your shin through the pad.",
      "Control the descent; don't let the weights slam."
    ],
    "common_faults": [
      {
        "fault": "Swinging the torso or using momentum to kick the weight up.",
        "correction": "Keep your back firmly against the pad and move the weight using only a controlled knee extension."
      },
      {
        "fault": "Allowing the pelvis or hips to lift off the seat during extension.",
        "correction": "Firmly pull upward on the side handles to keep your glutes anchored flat against the seat cushion."
      }
    ],
    "safety": {
      "precautions": [
        "Avoid aggressive knee hyperextension or snapping the joint locked at the top of the movement."
      ],
      "spotter": "not-needed"
    }
  },
  "measurement": {
    "load": {
      "convention": "weight-stack",
      "implements": 1,
      "kind": "external"
    },
    "profiles": [
      {
        "required": [
          "reps",
          "load"
        ],
        "optional": [
          "rpe",
          "rir",
          "tempo"
        ]
      }
    ],
    "records": {
      "e1rm": true,
      "volume": true
    },
    "reps_counted": "per-side"
  },
  "name": "Single-Leg Leg Extension",
  "previous_ids": [
    "oec:single-leg-extension"
  ],
  "provenance": {
    "generated": [
      "/name",
      "/summary",
      "/classification",
      "/anatomy",
      "/equipment",
      "/measurement",
      "/instructions",
      "/setup",
      "/relations"
    ],
    "license": "CC-BY-SA-4.0",
    "review": {
      "status": "machine-generated",
      "model": "gemini-3.8-flash",
      "at": "2026-10-31"
    },
    "sources": [
      {
        "title": "wger: Single Leg Extension",
        "url": "https://wger.de/en/exercise/71/view-base",
        "license": "CC-BY-SA-3.0",
        "author": "wger.de"
      }
    ]
  },
  "relations": [
    {
      "type": "variation-of",
      "target": "oec:leg-extension"
    },
    {
      "type": "substitute-for",
      "target": "oec:leg-extension"
    }
  ],
  "setup": {
    "position": "seated"
  },
  "status": "active",
  "summary": "An open-chain machine isolation exercise that targets the quadriceps of one leg at a time to build knee-extensor strength and correct side-to-side imbalances."
}